Systems and methods for synchronized control of electrical power system voltage profiles

ABSTRACT

Disclosed herein are various embodiments of systems and methods for controlling a voltage profile delivered to a load in an electric power system. According to various embodiments, an electric power system may include an electric power line, a variable tap transformer, and a capacitor bank. The variable tap transformer may include a plurality of tap positions. A tap change controller may be coupled with the variable tap transformer and may control the tap positions of the variable tap transformer. A capacitor bank controller may be coupled with the capacitor bank and may selectively couple the capacitor bank to the electric power line. The tap change controller and the capacitor bank controller may share system information related to the voltage profile along the electric power line and to change the voltage profile along the line using the variable tap transformer and the capacitor bank depending on the system information.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/251,180, filed Oct. 13, 2009, andentitled “SYNCHRONIZED REAL-TIME CONTROL FOR OPTIMIZING SYSTEM VOLTAGEPROFILES,” and U.S. patent application Ser. No. 12/903,038, and entitled“SYSTEMS AND METHODS FOR SYNCHRONIZED CONTROL OF ELECTRICAL POWER SYSTEMVOLTAGE PROFILES,” which are hereby incorporated by reference in theirentirety.

TECHNICAL FIELD

This disclosure relates to systems and methods for controllingelectrical power system voltage profiles and, more particularly, tosystems and methods for controlling electrical power system voltageprofiles using capacitor banks and on-load tap changers.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the disclosure aredescribed, including various embodiments of the disclosure withreference to the figures, in which:

FIG. 1 illustrates a simplified diagram of an electric power deliverysystem.

FIG. 2 illustrates a block diagram of an electric power delivery systemincluding an on-load tap changer and a shunt capacitor bank system.

FIG. 3 illustrates a diagram of a voltage profile for an on-load tapchange controller.

FIG. 4 illustrates a flowchart of a method for controlling electricalpower system voltage profiles.

DETAILED DESCRIPTION

The embodiments of the disclosure will be best understood by referenceto the drawings. It will be readily understood that the components ofthe disclosed embodiments, as generally described and illustrated in thefigures herein, could be arranged and designed in a wide variety ofdifferent configurations. Thus, the following detailed description ofthe embodiments of the systems and methods of the disclosure is notintended to limit the scope of the disclosure, as claimed, but is merelyrepresentative of possible embodiments of the disclosure. In addition,the steps of a method do not necessarily need to be executed in anyspecific order, or even sequentially, nor need the steps be executedonly once, unless otherwise specified.

In some cases, well-known features, structures or operations are notshown or described in detail. Furthermore, the described features,structures, or operations may be combined in any suitable manner in oneor more embodiments. It will also be readily understood that thecomponents of the embodiments, as generally described and illustrated inthe figures herein, could be arranged and designed in a wide variety ofdifferent configurations.

Several aspects of the embodiments described are illustrated as softwaremodules or components. As used herein, a software module or componentmay include any type of computer instruction or computer executable codelocated within a memory device that is operable in conjunction withappropriate hardware to implement the programmed instructions. Asoftware module or component may, for instance, comprise one or morephysical or logical blocks of computer instructions, which may beorganized as a routine, program, object, component, data structure,etc., that performs one or more tasks or implements particular abstractdata types.

In certain embodiments, a particular software module or component maycomprise disparate instructions stored in different locations of amemory device, which together implement the described functionality ofthe module. Indeed, a module or component may comprise a singleinstruction or many instructions, and may be distributed over severaldifferent code segments, among different programs, and across severalmemory devices. Some embodiments may be practiced in a distributedcomputing environment where tasks are performed by a remote processingdevice linked through a communications network. In a distributedcomputing environment, software modules or components may be located inlocal and/or remote memory storage devices. In addition, data being tiedor rendered together in a database record may be resident in the samememory device, or across several memory devices, and may be linkedtogether in fields of a record in a database across a network.

Embodiments may be provided as a computer program product including anon-transitory machine-readable medium having stored thereoninstructions that may be used to program a computer (or other electronicdevice) to perform processes described herein. The non-transitorymachine-readable medium may include, but is not limited to, hard drives,floppy diskettes, optical disks, CD-ROMs, DVD-ROMs, ROMs, RAMs, EPROMs,EEPROMs, magnetic or optical cards, solid-state memory devices, or othertypes of media/machine-readable medium suitable for storing electronicinstructions.

Electrical power generation and delivery systems are designed togenerate, transmit, and distribute electric energy to loads. Electricalpower generation and delivery systems may include equipment such aselectrical generators, electrical motors, power transformers, powertransmission and distribution lines, circuit breakers, switches, buses,transmission lines, voltage regulators, capacitor banks, and the like.Such equipment may be monitored, controlled, automated, and/or protectedusing intelligent electronic devices (IEDs) that receive electric powersystem information from the equipment, make decisions based on theinformation, and provide monitoring, control, protection, and/orautomation outputs to the equipment.

Consistent with embodiments disclosed herein, electrical powergeneration and delivery system equipment may be monitored and protectedfrom various malfunctions and/or conditions using one or more IEDs. Forexample, an IED may be configured to protect the electrical power systemequipment from abnormal conditions such as electrical short circuits,voltage overloads, frequency excursions, voltage functions, and thelike. In some embodiments, to protect electrical power system equipment,an IED may isolate equipment from the rest of a system upon detecting anabnormal condition (e.g., a fault) in the equipment and/or the system.

To protect a variety of electrical power system equipment, a variety ofIEDs designed to protect different equipment may be included in thesystem. Such IEDs may include one or more protective relays, tap changecontrollers, shunt capacitor bank controllers, differential relays,directional relays, bus protection relays, transformer protectionrelays, and the like. In some embodiments, an electrical powergeneration and delivery system may include shunt capacitor banks (SCBs)configured to provide capacitive reactive power support and compensationin high and/or low voltage situations in the electrical power system.For example, when reactive power or voltage along a transmission ordistribution line included in the electrical power system is below aspecified threshold, the shunt capacitors capacitor banks within the(s)SCB may be switched on to maintain the reactive power or voltagelevels and/or range of levels along the transmission line at a certainspecified voltage level and/or range of voltage levels. In someembodiments, the functionality of the SCB may be controlled using anIED.

An electrical power generation and delivery system may further includean on-load tap changer (OLTC) configured to control the voltage ofelectric power delivered to loads associated with the electrical powersystem. In some embodiments, an OLTC may include a transformer with oneor more windings that includes variable and/or set tap points that canbe adjusted to deliver a specified voltage output. In certainembodiments, as described in detail below, the tap points of thetransformer in an OLTC may be adjusted to deliver a voltage outputhaving a specified voltage profile to one or more loads included in anelectrical power system. Like the SCB, the functionality of the OLTC maybe controlled using an IED.

FIG. 1 illustrates a simplified diagram of an electric power generationand delivery system 100 consistent with embodiments disclosed herein.The electric power generation and delivery system 100 may include, amongother things, an electric generator 102, configured to generate anelectrical power output, which in some embodiments may be a sinusoidalwaveform. Although illustrated as a one-line diagram for purposes ofsimplicity, electrical power generation and delivery system 100 may alsobe configured as three phase power system.

A step-up power transformer 104 may be configured to increase the outputof the electric generator 102 to a higher voltage sinusoidal waveform. Abus 106 may distribute the higher voltage sinusoidal waveform to atransmission line 108 that in turn may connect to a bus 120. In certainembodiments, the system 100 may further include one or more breakers112-118 that may be configured to be selectively actuated to reconfigureelectric power delivery system 100. A step down power transformer 122may be configured to transform the higher voltage sinusoidal waveform tolower voltage sinusoidal waveform that is suitable for delivery to aload 124.

The IEDs 126-138, illustrated in FIG. 1, may be configured to control,monitor, protect, and/or automate the electric power system 100. As usedherein, an IED may refer to any microprocessor-based device thatmonitors, controls, automates, and/or protects monitored equipmentwithin an electric power system. An IED may include, for example, remoteterminal units, differential relays, distance relays, directionalrelays, feeder relays, overcurrent relays, voltage regulator controls,voltage relays, breaker failure relays, generator relays, motor relays,automation controllers, bay controllers, meters, recloser controls,communications processors, computing platforms, programmable logiccontrollers (PLCs), programmable automation controllers, input andoutput modules, motor drives, and the like. In some embodiments, IEDs126-138 may gather status information from one or more pieces ofmonitored equipment. Further, IEDs 126-138 may receive informationconcerning monitored equipment using sensors, transducers, actuators,and the like. Although FIG. 1 illustrates separate IEDs monitoring asignal (e.g., IED 134) and controlling a breaker (e.g., IED 136), thesecapabilities may be combined into a single IED.

FIG. 1 illustrates various IEDs 126-138 performing various functions forillustrative purposes and does not imply any specific arrangements orfunctions required of any particular IED. In some embodiments, IEDs126-138 may be configured to monitor and communicate information, suchas voltages, currents, equipment status, temperature, frequency,pressure, density, infrared absorption, radio-frequency information,partial pressures, viscosity, speed, rotational velocity, mass, switchstatus, valve status, circuit breaker status, tap status, meterreadings, and the like. Further, IEDs 126-138 may be configured tocommunicate calculations, such as phasors (which may or may not besynchronized as synchrophasors), events, fault distances, differentials,impedances, reactances, frequency, and the like. IEDs 126-138 may alsocommunicate settings information, IED identification information,communications information, status information, alarm information, andthe like. Information of the types listed above, or more generally,information about the status of monitored equipment, may be generallyreferred to herein as monitored system data.

In certain embodiments, IEDs 126-138 may issue control instructions tothe monitored equipment in order to control various aspects relating tothe monitored equipment. For example, an IED (e.g., IED 136) may be incommunication with a circuit breaker (e.g., breaker 114), and may becapable of sending an instruction to open and/or close the circuitbreaker, thus connecting or disconnecting a portion of a power system.In another example, an IED may be in communication with a recloser andcapable of controlling reclosing operations. In another example, an IEDmay be in communication with a voltage regulator and capable ofinstructing the voltage regulator to tap up and/or down. Information ofthe types listed above, or more generally, information or instructionsdirecting an IED or other device to perform a certain action, may begenerally referred to as control instructions.

IEDs 126-138 may be communicatively linked together using a datacommunications network, and may further be communicatively linked to acentral monitoring system, such as a supervisory control and dataacquisition (SCADA) system 142, an information system (IS) 144, and/orwide area control and situational awareness (WCSA) system 140. Theembodiments illustrated in FIG. 1 are configured in a star topologyhaving an automation controller 150 at its center, however, othertopologies are also contemplated. For example, the IEDs 126-138 may becommunicatively coupled directly to the SCADA system 142 and/or the WCSAsystem 140. The data communications network of the system 100 mayutilize a variety of network technologies, and may comprise networkdevices such as modems, routers, firewalls, virtual private networkservers, and the like. Further, in some embodiments, the IEDs 126-138and other network devices may be communicatively coupled to thecommunications network through a network communications interface.

Consistent with embodiments disclosed herein, IEDs 126-138 may beconnected at various points to the electric power generation anddelivery system 100. For example, IED 134 may monitor conditions ontransmission line 108. IEDs 126, 132, 136, and 138 may be configured toissue control instructions to associated breakers 112-118. IED 130 maymonitor conditions on a bus 152. IED 128 may monitor and issue controlinstructions to the electric generator 102, while IED 126 may issuecontrol instructions to breaker 116.

In certain embodiments, various IEDs 126-138 and/or higher level systems(e.g., SCADA system 142 or IS 144) may be facilitated by the automationcontroller 150. The automation controller 150 may also be referred to asa central IED or access controller. In various embodiments, theautomation controller 150 may be embodied as the SEL-2020, SEL-2030,SEL-2032, SEL-3332, SEL-3378, or SEL-3530 available from SchweitzerEngineering Laboratories, Inc. of Pullman, Wash., and also as describedin U.S. Pat. No. 5,680,324, U.S. Pat. No. 7,630,863, and U.S. PatentApplication Publication No. 2009/0254655, the entireties of which areincorporated herein by reference.

IEDs 126-138 may communicate information to the automation controller150 including, but not limited to, status and control information aboutthe individual IEDs 126-138, IED settings information, calculations madeby the individual IEDs 126-138, event (e.g., a fault) reports,communications network information, network security events, and thelike. In some embodiments, the automation controller 150 may be directlyconnected to one or more pieces of monitored equipment (e.g., electricgenerator 102 or breakers 112-118).

The automation controller 150 may also include a local human machineinterface (HMI) 146. In some embodiments, the local HMI 146 may belocated at the same substation as automation controller 150. The localHMI 146 may be used to change settings, issue control instructions,retrieve an event report, retrieve data, and the like. The automationcontroller 150 may further include a programmable logic controlleraccessible using the local HMI 146. A user may use the programmablelogic controller to design and name time coordinated instruction setsthat may be executed using the local HMI 146. In some embodiments, thetime coordinated instruction sets may be stored in computer-readablestorage medium (not shown) on automation controller 150.

In certain embodiments, a time coordinated instruction set may bedeveloped outside the automation controller 150 (e.g., using WCSA system140, or SCADA system 142) and transferred to the automation controller150 or through the automation controller 150 to the IEDs 126-138 or, inother embodiments without the automation controller 150, directly to theIEDs 126-138, using a communications network, using a USB drive, or thelike. For example, time coordinated instruction sets may be designed andtransmitted via WCSA system 140. Further, in some embodiments, theautomation controller 150 or IEDs 126-138 may be provided from themanufacturer with pre-set time coordinated instruction sets. U.S. patentapplication Ser. No. 11/089,818 (U.S. Patent Application PublicationNumber 2006/0218360) titled Method and Apparatus for Customization,describes such a method, and is hereby incorporated by reference in itsentirety.

The automation controller 150 may also be communicatively coupled to atime source (e.g., a clock) 148. In certain embodiments, the automationcontroller 150 may generate a time signal based on the time source 148that may be distributed to communicatively coupled IEDs 126-138. Basedon the time signal, various IEDs 126-138 may be configured to collecttime-aligned data points including, for example, synchrophasors, and toimplement control instructions in a time coordinated manner. In someembodiments, the WCSA system 140 may receive and process thetime-aligned data, and may coordinate time synchronized control actionsat the highest level of the electrical power generation and deliverysystem 100. In other embodiments, the automation controller 150 may notreceive a time signal, but a common time signal may be distributed toIEDs 126-138.

The time source 148 may also be used by the automation controller 150for time stamping information and data. Time synchronization may behelpful for data organization, real-time decision-making, as well aspost-event analysis. Time synchronization may further be applied tonetwork communications. The time source 148 may be any time source thatis an acceptable form of time synchronization, including, but notlimited to, a voltage controlled temperature compensated crystaloscillator, Rubidium and Cesium oscillators with or without a digitalphase locked loops, microelectromechanical systems (MEMS) technology,which transfers the resonant circuits from the electronic to themechanical domains, or a global positioning system (GPS) receiver withtime decoding. In the absence of a discrete time source 148, theautomation controller 150 may serve as the time source 148 bydistributing a time synchronization signal.

To maintain voltage and reactive power within certain limits for safeand reliable power delivery, an electrical power generation and deliverysystem may include SCBs (e.g., capacitor 110) configured to providecapacitive reactive power support and compensation in high and/or lowvoltage conditions within the electrical power system. For example, whenpower along a transmission line included in the electrical power systemmeets certain predetermined criteria, the capacitors within the SCB maybe switched on (e.g., via breaker 118) by an IED to maintain a properbalance of reactive power. Further, an electrical power generation anddelivery system may include an OLTC configured to control the quality ofelectric power delivered to loads associated with the electrical powersystem by varying transformer tap positions within the OLTC. Like theSCB, the functionality of the OLTC may be controlled using an IED.

FIG. 2 illustrates a block diagram of an electric power generation anddelivery system 200 including an OLTC 206 and an SCB 222 systemconsistent with embodiments disclosed herein. Although illustrated assingle phase one-line 230 system for purposes of simplicity, electricalpower generation and delivery system 200 may also be configured as threephase power system.

The OLTC 206 may be communicatively coupled to an IED generallydescribed herein as an OLTC control module 210. The OLTC control module210 may receive monitored system data from the OLTC 206. In certainembodiments, the OLTC control module 210 may be configured to utilizemonitored system current and voltage signals at levels less than thosepresent in the OLTC 206 and/or on the line 230. Accordingly, the OLTCcontrol module 210 may be coupled to the line 230 via a step downvoltage transformer 214 and/or a current transformer 212. The step downvoltage transformer 214 may be configured to step down the voltage alongthe line 230 to a secondary voltage V_(L), having a magnitude that canbe monitored and measured by the OLTC control module 210 (e.g., from aline 230 voltage of 12 kV to an OLTC control module 210 voltage of120V). Similarly, the current transformer 212 may be configured to stepdown the line 230 current to a secondary current I_(L) having amagnitude that can be monitored and measured by the OLTC control module210 (e.g., from a line 230 current of 200 amps to a OLTC control module210 current of 0.2 amps). In certain embodiments, the OLTC 206 mayfurther include a second step down voltage transformer 216 for useduring a reverse load condition, wherein the generator 202 may beswitched into the system on the load side. While the step down voltagetransformers 214 and 216 and/or current transformer 212 are illustratedin FIG. 2 as being included in the OLTC 206, other configurations of theOLTC 206, the OLTC control module 210, the step down voltagetransformers 214 and 216, and/or the current transformer 212 may also beimplemented.

In certain embodiments, the OLTC control module 210 may include aprocessor 240 and/or microcontroller (not shown) configured to receivethe secondary voltage V_(L) and secondary current I_(L) signals, filterthe signals, and process the signals to calculate phasors havingmagnitudes and phase angles corresponding to the signals. The phasorsmay be used by the processor and/or microcontroller included in the OLTCcontrol module 210 to determine whether a tap change in a variable taptransformer 208 included in the OLTC 210 is needed to adjust the voltageprofile provided to the load 204 into a center-band or specified voltageprofile (e.g., 120V). If such an adjustment is needed, the OLTC controlmodule 210 may direct the OLTC 206 to make such an adjustment to thevariable tap transformer 208 by issuing control instructions via acontrol line 218. In certain embodiments, the OLTC control module 210may be configured to account for line resistances and reactances of theline 230 in directing the OLTC 206 to adjust the voltage profileprovided to the load 204. Further, in some embodiments, the OLTC controlmodule 210 may be determined based on the calculated phasors whether thevoltage profile of the measured signal along the line 230 is within acertain range of specified voltage profiles and, if the measured voltageprofile is outside such a range, direct the OLTC 206 to make neededadjustments.

FIG. 3 illustrates a diagram of a voltage profile 300 for an OLTCcontrol module. As shown in FIG. 3, a specified voltage profile 300 mayinclude an in-band area 314 representing a voltage range around a centerband 306 voltage level between out-of-band (OOB) voltage levels 304 and308. A high OOB area 310 may extend between a maximum voltage and OOBvoltage level 304. Similarly, a low OOB area 302 may extend between aminimum voltage and OOB voltage level 304. Although FIG. 3 includesspecified voltage levels for discussion purposes, other voltage levelsmay be used.

In the illustrated example, a center-band voltage 306 in a specifiedvoltage profile may be at 120V. The center-band voltage 306 may beincluded within an in-band area 314 specified to have a range of 120V±2V(i.e., a total range of 4V). A high OOB area 310 may extend between amaximum voltage of 128V and an OOB voltage level 308 of 122V. Similarly,a low OOB area 302 may extend between a minimum voltage of 112V and anOOB voltage level 304 of 118V.

Consistent with embodiments disclosed herein, when a measured voltageprofile received by an OLTC control module (e.g., OLTC control module210) is within the high OOB area 310, the OLTC control module may directthe variable tap transformer included in an OLTC (e.g., OLTC 206) toadjust its tap such that the measured voltage profile returns to thein-band area 314 by, for example, issuing a corresponding command to theOLTC. Similarly, when a measured voltage profile received by an OLTCcontrol module is within the low OOB area 302, the OLTC control modulemay direct the variable tap transformer included in the OLTC to adjustits tap such that the measured voltage profile returns to the in-bandarea 314 by issuing a corresponding command to the OLTC. In someembodiments, the command issued by the OLTC control module to the OLTCmay direct the OLTC to adjust its tap, but to do so in a time-controlledmanner so as to not cause abrupt changes in the voltage profile alongthe transmission line.

In certain embodiments, a specified voltage profile 300 may include ahigh dead-band area 312 between a maximum voltage of, for example, 128V,and a runback high voltage of, for example, 130V. If a measured voltageprofile received by an OLTC control module is within or above the highdead-band area 312 (i.e., indicating an extreme voltage condition), theOLTC control module may direct the OLTC to adjust its tap more rapidly(e.g., with little or no time delay) such that the measured voltageprofile returns to the in-band area 314 prior to damaging any componentsof the electrical power system delivery system. The OLTC control modulemay direct the OLTC similarly when the measured voltage profile iswithin or below a low dead-band area 316 between a minimum voltage(e.g., 112V) and a runback low voltage (e.g., 110V). Further, in someembodiments, the OLTC control module may only direct the OLTC to adjustits tap to return the measured voltage profile returns to the in-bandarea when the measured voltage is within or above the high dead-bandarea 312 or within or below the low dead-band area 316.

Referring back to FIG. 2, an SCB system 222 may be included in theelectric power generation and delivery system 200 in addition to theOLTC 206. In certain embodiments, the SCB system 222 may be coupledbetween the line 230 and ground. In some embodiments, signals (e.g.,monitored system data and the like) may be received by the OLTC controlmodule 210 via an OLTC interface 238 configured to communicativelyinterface the OLTC control module 210 with other components of thesystem 200. The functionality of the OLTC control module 210 disclosedherein may be implemented using processor-executable instructions storedon a computer-readable storage medium 242 included within and/orexternal to the OLTC control module 210. In certain embodiments, theinstructions stored on the computer-readable storage medium 242 maydefine functional modules that when executed by the processor 240 causethe processor 240 to perform the disclosed methods and functions of theOLTC control module 210.

As previously discussed, the SCB system 222 may include one or morecapacitors configured to provide capacitive reactive power compensationin high and/or low voltage situations in the electrical power system200. For example, when the voltage profile along the line 230 meetscertain predetermined criteria, capacitors within the SCB 222 may beswitched on via a breaker 228 to maintain the power along the line 230at a certain specified voltage profile.

The SCB system 222 may be communicatively coupled to an IED generallydescribed herein as an SCB control module 220. The SCB control module220 may be configured to control the functionality of SCB system 222.The SCB control module 220 may receive monitored system data from theSCB 222 and/or the line 230. For example, the SCB control module 220 mayreceive monitored system data relating the measured current through theline 230 via a current transformer 232. Further, the SCB control module220 may receive line 230 voltage signals using potential transformers(not shown) connected to either the line 230, the branch the SCB system222 is coupled to, or within the SCB system 222 itself. In someembodiments, the SCB control module 220 may further receive voltageinformation from a neutral side of the SCB system 222 and ground using apotential transformer 224.

In some embodiments, signals (e.g., monitored system data and the like)may be received by the SCB control module 220 via a SCB interface 244configured to communicatively interface the SCB control module 220 withother components of the system 200. The SCB control module 220 mayinclude one or more processors 246 configured to execute instructionsstored on a computer-readable storage medium 248 included within the SCBcontrol module 220 and/or external to the SCB control module 220. Incertain embodiments, the instructions stored on the computer-readablestorage medium 248 may define functional modules that when executed bythe processor 246 cause the processor 246 to perform the disclosedmethods and functions of the SCB control module 220. For example,consistent with some embodiments, the processor 246 of the SCB controlmodule 220 may be configured to determine if electric power delivered tothe load 204 is within certain parameters in terms of the reactive powerdelivered thereto. If the delivered reactive power is not within certainparameters, the SCB control module 220 may direct the SCB 222 to beactivated via control line 226 coupled to the SCB interface 244 using,for example, the breaker 228.

In some electric power delivery systems 200, the OLTC 206 and the SCB222 may operate independently of each other. In some circumstances,however, independent operation of the OLTC 206 and SCB 222 may causeunnecessary switching operations in both devices. For example, incertain conditions, controlling a voltage profile delivered to the load204 may be better achieved by utilizing the OLTC 206 rather than the SCB222. Similarly, in certain other conditions, controlling a voltageprofile delivered to the load 204 may be better achieved by utilizingthe SCB 222 rather than the OLTC 206.

Consistent with some embodiments, the OLTC control module 210 and theSCB control module 220 may operate together to coordinate the operationof the OLTC 206 and SCB 222 based on detected system conditions. Toachieve such coordinated functionality between the two devices, the OLTCcontrol module 210 and the SCB control module 220 may be communicativelycoupled via a communications line 234. By coordinating the operation ofthe OLTC 206 and SCB 220, control of the voltage profile delivered tothe load 204 may be achieved and unnecessary switching operations inboth devices may be reduced. For example, in certain conditions, theOLTC control module 210 and SCB control module 220 may collectivelydetermine that control of the voltage profile delivered to the load 204is better achieved by utilizing the OLTC 206 rather than the SCB 222 andtake appropriate action to such effect. Similarly, in certain otherconditions, the OLTC control module 210 and SCB control module 220 maycollectively determine that control of the voltage profile delivered tothe load 204 may be better achieved by utilizing the SCB 222 rather thanthe OLTC 206 and take appropriate action to such effect.

In certain embodiments, the communications line 234 may be capable ofcommunicating synchronized phasor data (i.e., synchrophasors) betweenthe OLTC control module 210 and the SCB control module 220 used forcoordinating the actions of the devices. For example, in someembodiments, the OLTC control module 210 and the SCB control module 220may each generate synchronized phasor data from the electric powerdelivery system 200 based on the monitored system data they eachreceive, as well as a common time reference 236. The common timereference 236 may be provided by any time reference source common toboth the OLTC control module 210 and the SCB control module 220 such as,for example, an inter-range instrumentation group (IRIG) satellite basedtime reference, the WWV time signal from the National Institute ofStandards and Technology (NIST), the WWVB time signal from the NIST, alocal area network (LAN) time signal, or the like.

The OLTC control module 210 and the SCB control module 220 maycommunicate synchronized phasor data between each other serially and, insome embodiments, may operate as a real-time controller client andserver. In certain embodiments, the synchrophasor data may includevoltage or current magnitude information, phase angle information, andother monitored system data information received from the electricalpower generator and transmission system 200. In some embodiments, thesynchrophasor data may be communicated between the OLTC control module210 and the SCB control module 220 using, for example, a C37.118protocol. As discussed previously, based at least in part on thesynchrophasor data received from the other device, each of the OLTCcontrol module 210 and the SCB control module 220 may collectivelydetermine how to better control the voltage profile along the line 230delivered to the load 204.

FIG. 4 illustrates a flowchart of a method for controlling electricalpower system voltage profiles consistent with embodiments disclosedherein. In step 400 of the method, first system information relating tothe voltage profile along a line may be received by a tap changecontroller. In certain embodiments, the first system information mayrelate to the voltage profile along the line at a certain positionrelated to the position of a variable tap transformer coupled with theline and the tap change controller. In step 402, second systeminformation related to the voltage profile along the line may bereceived by a capacitor bank controller. The second system informationmay relate to the voltage profile along the line at a certain positionrelated to the position of a capacitor bank system selectivelycoupleable to the line and coupled to the capacitor bank controller.

In step 404 of the method, the tap change controller, the capacitor bankcontroller, and/or a centralized IED or system communicatively coupledwith the tap change controller and/or the capacitor bank controller maydetermine based on the first and/or second system information whetherthe voltage profile along the line needs to be changed based on a loadprofile associated with the line. Based on the determination, at step406, the tap change controller, the capacitor bank controller, and/or acentralized IED or system may control the voltage profile along the lineaccordingly by changing the tap position of the variable tap transformerand/or coupling the capacitor bank to the line.

While specific embodiments and applications of the disclosure have beenillustrated and described, it is to be understood that the disclosure isnot limited to the price configurations and components disclosed herein.Accordingly, many changes may be made to the details of theabove-described embodiments without departing from the underlyingprinciples of this disclosure. The scope of the present inventionshould, therefore, be determined only by the following claims.

What is claimed is:
 1. An intelligent electronic device (IED),comprising: a communication system configured to share systeminformation related to a voltage profile on an electric power line witha variable tap transformer and a shunt capacitor bank, the variable taptransformer including a plurality of tap positions selectivelycoupleable with the electric power line, and the shunt capacitor bankbeing selectively coupleable with the electric power line; a processorcommunicatively coupled to the communication system; and anon-transitory computer-readable storage medium communicatively coupledto the processor, the computer-readable storage medium storing aplurality of instructions that when executed by the processor cause theprocessor to change the voltage profile by controlling one of a tapposition of the variable tap transformer and a connection status of theshunt capacitor bank.
 2. The IED of claim 1, wherein the IED comprises atap change controller.
 3. The IED of claim 2, wherein the communicationsystem comprises a monitored equipment interface in communication withthe variable tap transformer; and wherein controlling the tap positioncomprises issuing an instruction to the variable tap transformer via themonitored equipment interface to selectively couple one of the pluralityof tap positions with the electric power line.
 4. The IED of claim 1,wherein the IED comprises a shunt capacitor bank controller.
 5. The IEDof claim 4, further comprising: wherein controlling the connectionstatus of the shunt capacitor bank comprises issuing an instruction toselectively couple the shunt capacitor bank to the electric power line.6. The IED of claim 5, wherein the instruction is configured to cause abreaker communicatively coupled to the shunt capacitor bank to close toselectively couple the shunt capacitor bank to the electric power line.7. The IED of claim 1, wherein the IED comprises an automationcontroller.
 8. The IED of claim 1, wherein the first and second systeminformation comprise synchronized phasor information.
 9. The IED ofclaim 1, wherein the first and second system information each compriseone of electric power line voltage information and line currentinformation.
 10. The IED of claim 1, further comprising a reference timesignal input, and wherein the reference time signal input is used tocoordinate a plurality of control instructions to change the voltageprofile by operation of one of the variable tap transformer and theshunt capacitor bank.
 11. The IED of claim 1, wherein the change to thevoltage profile maintains a voltage on the electric power line within apredetermined voltage range.
 12. The IED of claim 1, wherein the changeto the voltage profile optimizes the voltage profile delivered to a loadcommunicatively couple with the electric power line.
 13. A method forcontrolling a voltage profile delivered to a load in an electric powersystem, the method comprising: receiving, by an IED, a first systeminformation from a tap change controller communicatively coupled with avariable tap transformer coupled to an electric power line; receiving,by the IED, a second system information from a shunt capacitor bankcontroller communicatively coupled with a shunt capacitor bank includingat least one capacitor coupled to the electric power line; controlling,by one of the tap change controller and the shunt capacitor bankcontroller, the voltage profile of the electric power line based on thefirst and second system information using one of the variable taptransformer and the shunt capacitor bank.
 14. The method of claim 13,further comprising: receiving a reference time signal; and coordinatingan operation of one of the shunt capacitor bank and the variable taptransformer based on the reference time signal.
 15. The method of claim13, wherein each of the first system information and the second systeminformation relates to a voltage profile along the electric power line.16. The method of claim 15, further comprising controlling one of thetap change controller and the shunt capacitor bank controller tomaintain the voltage profile along the electric power line within apredetermined voltage range.
 17. The method of claim 13, wherein each ofthe first system information and the second system information comprisesynchronized phasor information.
 18. The method of claim 13, wherein theeach of the first system information and the second system informationcomprise one of a voltage of the electric power line and a current ofthe electric power line.
 19. The method of claim 13, wherein controllingthe voltage profile using the variable tap transformer comprisesadjusting a tap position coupled to the electric power line.
 20. Themethod of claim 13, wherein controlling the voltage profile using theshunt capacitor bank comprises selectively coupling the shunt capacitorbank to the electric power line.